IIRC, that is an API that Google's making available to developers. So, any of the music players on the market could theoretically add it as a feature. For the time being, there's bTunes, but it's clumsy, not getting support anymore, and constantly gets closed for taking too much of my Droid OG's memory.

Thanks. I actually have bTunes but didn't know it had that feature. However, I tried it's built-in voice command and it always pops up a text list of possible choices after the command so it's not hands (or eyes) free. Close but no cigar. Sad that program's been abandoned - it's so nice it a lot of ways.